Supreme Court had directed that bursting of crackers on Diwali and other festivals be limited to two hours and only "green firecrackers" be sold in Delhi

Delhi has been witnessing deteriorating air quality. (Representational)

New Delhi:

Delhi's air quality slipped to 'severe' category on Sunday due to unfavourable weather conditions as authorities warned that any trigger in form of fire crackers on New Year's eve or rise in vehicular emission would further increase the pollution level in the national capital.

In view of the 'severe' pollution level plaguing the national capital, the CPCB-led task force has directed implementing agencies of Delhi-NCR to take actions with "zero tolerance" to waste burning and construction activities and reiterated its call to strictly implement the Supreme Court order on bursting of fire crackers.

The Central Pollution Control Board (CPCB) data showed the overall air quality index (AQI) at the 'severe' level of 414.

The Centre-run System of Air Quality and Weather Forecasting (SAFAR) said the air quality would improve slightly "provided no additional local emissions are added on New Year's eve".

"The deterioration in moisture-laden wind speed from west may becoming fatal at this stage and any new trigger in terms of local emission, particularly from open fire, firecrackers and fossil fuel (vehicular pollution)will fast deteriorate the air quality and keep it in severe category," the SAFAR said.

The air quality slipped into severe category on Sunday morning for this fourth time in 10 days.

Delhi's air quality has been oscillating between very poor and severe category for the past ten days.

In NCR, Ghaziabad, Gurgaon, Faridabad and Noida recorded 'severe' air quality, the CPCB data said.

The overall PM2.5 level - fine particulate matter in the air with a diameter of less than 2.5 micrometer - was recorded at 318 and the PM10 level at 479 in Delhi, the CPCB said.

Delhi recorded its second-highest pollution level of the year last Sunday with an AQI of 450. The air quality remained 'severe' Monday and Tuesday.

There was a slight drop in the pollution level and the air quality moved to the 'very poor' category on Wednesday.

On Thursday, the air quality again worsened and turned 'severe' and since then it has been oscillating between very poor and severe.

An emergency meeting convened by the CPCB-led task force on Sunday after Delhi's air quality slipped to severe category also directed that while the measures already in force must continue, the enforcement on "ground needs to be stepped up particularly in hot spot areas" that are vulnerable to high pollution.

"The implementing agencies in Delhi and four neighbouring townsof Noida, Ghaziabad, Faridabad and Gurugram to be on high alert, carry out night patrolling, and take actions with zero tolerance to waste burning and construction activities," the task force said.

"The agencies must also ensure strict compliance to the orders of the Hon'ble Supreme Court regarding bursting of firecrackers," it said.

The CPCB-led task force had earlier written to local authorities and Delhi police and warned that instance of Diwali when gross violation of the Supreme Court order was observed should not be repeated.

The top court had in October directed that bursting of crackers on Diwali and other festivals be limited to two hours and only "green firecrackers" be sold in Delhi and the National Capital Region.

However, gross violations of the order were observed during Diwali with rampant burning of toxic firecrackers across the country.

"The deterioration in moisture laden wind speed from west may be becoming fatal at this stage and any new trigger in terms of local emission, particularly from open fire, firecrackers and fossil fuel will fast deteriorate the air quality and keep it in severe category," the SAFAR said.

Indian Meteorological Department and the SAFAR informed that air quality is likely to remain in 'severe' category owing to low wind speed which is highly unfavourable for dispersion of pollutants.

The authorities warned that moderate fog and emissions during night hours may result in deterioration in air quality and the situation may prevail till Wednesday.